/**
 * Copyright (c) 2000-2006 Liferay, LLC. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.pcbly.web.components.utils.security;


import java.io.UnsupportedEncodingException;

import java.security.Key;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.Provider;
import java.security.SecureRandom;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.pcbly.web.components.utils.ServerDetector;

import sun.misc.BASE64Encoder;

/**
 * <a href="Encryptor.java.html"><b><i>View Source</i></b></a>
 *
 * @author  Brian Wing Shun Chan
 *
 */
public class Encryptor {

	public static final String ENCODING = "UTF-8";

	public static final String DIGEST_ALGORITHM = "SHA";

	public static final String KEY_ALGORITHM = "DES";

	public static final String SUN_PROVIDER_CLASS =
		"com.sun.crypto.provider.SunJCE";

	public static final String IBM_PROVIDER_CLASS =
		"com.ibm.crypto.provider.IBMJCE";

	public static final String PROVIDER_CLASS = "com.sun.crypto.provider.SunJCE";

	public static Key generateKey() throws EncryptorException {
		return generateKey(KEY_ALGORITHM);
	}

	public static Key generateKey(String algorithm) throws EncryptorException {
		try {
			Security.addProvider(getProvider());

			KeyGenerator generator = KeyGenerator.getInstance(algorithm);
			generator.init(56, new SecureRandom());

			Key key = generator.generateKey();

			return key;
		}
		catch (Exception e) {
			throw new EncryptorException(e);
		}
	}

	@SuppressWarnings("unchecked")
	public static Provider getProvider()
		throws ClassNotFoundException, IllegalAccessException,
			   InstantiationException {

		Class providerClass = null;

		try {
			providerClass = Class.forName(PROVIDER_CLASS);
		}
		catch (ClassNotFoundException cnfe) {
			if ((ServerDetector.isWebSphere()) &&
				(PROVIDER_CLASS.equals(SUN_PROVIDER_CLASS))) {

				_log.warn(
					"WebSphere does not have " + SUN_PROVIDER_CLASS +
						", using " + IBM_PROVIDER_CLASS + " instead");

				providerClass = Class.forName(IBM_PROVIDER_CLASS);
			}
			else if (System.getProperty("java.vm.vendor").equals(
						"IBM Corporation")) {

				_log.warn(
					"IBM JVM does not have " + SUN_PROVIDER_CLASS + ", using " +
						IBM_PROVIDER_CLASS + " instead");

				providerClass = Class.forName(IBM_PROVIDER_CLASS);
			}
			else {
				throw cnfe;
			}
		}

		return (Provider)providerClass.newInstance();
	}

	

	public static String digest(String text) {
		return digest(DIGEST_ALGORITHM, text);
	}

	public static String digest(String algorithm, String text) {
		MessageDigest mDigest = null;

		try{
			mDigest = MessageDigest.getInstance(algorithm);

			mDigest.update(text.getBytes(ENCODING));
		}
		catch (NoSuchAlgorithmException nsae) {
			nsae.printStackTrace();
		}
		catch (UnsupportedEncodingException uee) {
			uee.printStackTrace();
		}

		byte raw[] = mDigest.digest();

		return (new BASE64Encoder()).encode(raw);
	}

	public static String encrypt(Key key, String plainText)
		throws EncryptorException {

		try {
			Security.addProvider(getProvider());

			Cipher cipher = Cipher.getInstance(key.getAlgorithm());
			cipher.init(Cipher.ENCRYPT_MODE, key);

			byte[] decryptedBytes = plainText.getBytes(ENCODING);
			byte[] encryptedBytes = cipher.doFinal(decryptedBytes);

			String encryptedString = Base64.encode(encryptedBytes);

			return encryptedString;
		}
		catch (Exception e) {
			throw new EncryptorException(e);
		}
	}
	public static String decrypt(Key key, String encryptedString)
	    throws EncryptorException {

	    try {
	    	Security.addProvider(getProvider());
	    	
	    	Cipher cipher = Cipher.getInstance(key.getAlgorithm());
	    	cipher.init(Cipher.DECRYPT_MODE, key);
	    	
	    	byte[] encryptedBytes = Base64.decode(encryptedString);
	    	byte[] decryptedBytes = cipher.doFinal(encryptedBytes);
	    	
	    	String decryptedString = new String(decryptedBytes, ENCODING);
	    	
	    	return decryptedString;
	    }
	    catch (Exception e) {
	    	throw new EncryptorException(e);
	    }
    }
	
	private static Log _log = LogFactory.getLog(Encryptor.class);

}